Electrowetting display devices are known, for example from international patent application no. WO 2003/071346. In an off state of such a display device an oil covers the area of a pixel of the display. In an on state the oil is retracted so as not to cover the pixel area. To switch the pixel into the on state a voltage is applied across the oil via an electrically conductive fluid immiscible with the oil, which exerts an electrostatic force on the conductive fluid, and to switch the pixel into the off state the voltage is switched off. Thus, for example, where the oil is coloured, a radiation beam passing through the pixel when in the off state passes through the oil and is imparted with colour, but does not pass through the oil with the pixel in the on state, and so its colour remains substantially unchanged.
A disadvantage of this display device is that when a voltage is applied to switch the pixel to the on state, the on state is not maintained. This results in poor quality images provided by the display device, especially over longer periods of time when the on state of pixels needs to be sustained.
It is an object of the present invention to reduce the cause of this disadvantage.